Animal Body Systems Lecture 12 PDF

Biol 224.3 – Animal Body Systems Lecture 12: Animal Locomotion: Skeleton & Muscles Dr Joan Forder Supplementary Reading: Textbook (5th Edition, Chapter 43, pages 1179-1197) 159 Where we ar...

Biol 224.3 – Animal Body Systems Lecture 12: Animal Locomotion: Skeleton & Muscles Dr Joan Forder Supplementary Reading: Textbook (5th Edition, Chapter 43, pages 1179-1197) 159 Where we are going Types of animal skeletons Hydrostatic Exoskeleton Endoskeleton Bone tissue Calcium regulation Three types of muscle Muscle structure Muscle physiology Levers Sarcomeres 16 0  Animal Skeletons For body support, locomotion, protection Three broad categories of skeletons: Hydrostatic Exoskeleton Endoskeleton exposed to bodily fluids limited protection must be shed for and H+ as a byproduct body growth (ecdysis) of metabolism 161  Sea Anemones Hydrostatic Skeleton Structure consisting of a muscles surrounded by a compartment or compartments filled with fluid under pressure Contraction and relaxation of muscles change the shape of the animal Fig. 43.11, p. 1189 contraction & constriction to move. Cnidarians Flatworms Roundworms Annelids Fig. 43.12, p. 1190  Exoskeleton Rigid external body covering Provides support for the body Can protect delicate internal tissues need boys Incompressible within. Athropods with a Chitinous Cuticle Force of muscle Fig. 43.13, p. 1190 contraction is applied against the covering Exoskeleton is formed by Functions: secretions from the To protect against dehydration underlying epidermis. Act as armour against predators Provides levers against which muscles work 163  Muscles Attached to an Exoskeleton Arthropod exoskeleton has moveable joints, flexed and extended by muscles. Most muscles attach directly to the cuticle by extensions of the myofibrils Extend from the inside surface of one section of cuticle to the inside surface of another section Since the sections are separated by flexible cuticle, contraction results in movement about the joint. muscles directly Grasshopper attached to exo-skeleton. 164 Fig. 43.14, p. 1191  Endoskeleton Supports the body by rigid structures (such as bones) within the body Also protects delicate internal tissues Force of muscle contraction is applied against supporting structures In vertebrates, endoskeleton is the primary skeletal system 165  Animal Skeletons Two types of endoskeletons e.g. Echinoderms calcium easily carbonate & dissolved in protein fibers acid e.g. Vertebrates > - HUMANS calcium phosphate & more protein fibers resistant to acid internal store of Ca++ & PO4-  The Human Skeleton Axial skeleton Skull, vertebral column, sternum, and ribcage Appendicular skeleton Shoulder, hip, leg, and arm bones 167 Fig. 43.15a, p. 1192 Mammalian Skeletons: Comparison Lemur Monkey Gliding Racoon Tree dwelling different depending on environment 168 Terrestrial Fig. 43.15b,c,d p. 1192  Bone Tissues Complex organs built from multiple tissues (nerves, blood vessels, bone BONES tissue) compact - > Compact bone regions (outer surface) Dones No spaces except microscopic spongy > - canals of the osteons very tiny openings bones Spongy bone regions Open into larger spaces Spaces filled by marrow red (primary source of new red blood cells) and/or new RBC's yellow (adipose tissue) RBC's have a limited life span.  ca2t release of Mineral Storage = neurotransmitters Calcium and phosphate ions are constantly deposited and withdrawn from bones. Hormonal controls maintain a concentration of Ca2+ ions at optimal levels in blood and extracellular fluids. Calcium Regulation Vertebrate skeleton relies on Ca++ homeostasis Blood Ca++ tightly regulated by endocrine negative feedback loops will inhibit further production. Chomeostasis) What other physiological process relies on Ca++? Figure 40.11 171  Muscles Responsible for movement of body Contractile cells are found in all animals True muscle evolved first in Cnidarians Contraction (shortening) based on interaction between: - supporting filaments (actin) and - a motor protein (myosin) Encyclopédie de Diderot, plate 1-143.jpg” from Wikimedia (in public domain, 172 accessed May 2014) Three Types of Vertebrate Muscle What does this mean? Skeletal & Cardiac muscle Striated Unstriated muscle muscle Skeletal Cardiac Smooth muscle muscle muscle Voluntary Involuntary muscle muscle muscle contraction neurogenic by Muscle myogenic itself. contractions from nervous system stimulus All muscle is bioelectric. (produces a membrane action potential) 173  Skeletal Muscle Most vertebrates have more than 600 skeletal muscles Consist of bundles of elongated, cylindrical cells called muscle fibres that run the entire length of the muscle Formed by a fusion of cells called myoblasts # of myoblasts fibers = together Contains multiple nuclei Cells held in parallel bundles by sheaths of connective tissue tendons attach to the bone. A Sheaths merge with the tendons TOSUPP g + 02 L Have an extensive network of blood vessels 174  Skeletal Muscle Cell Average length is 3 cm, up to 30 cm. 175 Image source from Wikipedia article “Muscle”, accessed January 2013. Skeletal Muscle Structure Within each muscle fibre are longitudinal bundles of contractile proteins called myofibrils. orderly protein arrangement produces striated appearance contraction stimulated by motor neurons (from somatic nervous system) actin, myosin & other proteins 176 Functional Divisions of the Vertebrate Nervous System See 42.54 177 Physiology of Vertebrate Skeletal Muscle shortening of a muscle generates a force & movement contraction & constriction e.g. rotator cuff muscles in human shoulder joint Skeletal muscle actively shortens but passively relaxes. Hint: try this link if GIF doesn't work Sliding filament theory explains muscle contraction. 178  Physiology of Vertebrate Skeletal Muscle Triceps brachii Shortening of a muscle generates a force & Biceps movement brachii on how a where dependent it is attached. Muscles generally grouped as antagonistic pairs around joints Figure 43.17 179  Working as a Lever proximal-speed distal = strength e close t Muscles can be Figure 43.17 attached proximal to the joint or distal from ↓ the joint further from moving joint Proximal insertion favours speed; distal insertion favours strength The fulcrum can also vary in position, favouring either speed or strength  Sarcomere Structure 1 Myofibril = many sarcomeres Myofilaments: - Thick filaments (Myosin) – A band - Thin filament (Actin) – I band H zone – Myosin only, bisected by M line so it can extend/shorten. Z disk anchors actin, M line anchors myosin mysi actin madeu- R notinintera Fig 43.3  Sliding Filament Theory > - not pletely proven Fig 43.3 move ↳ Troponin and Tropomyosin (actin) regulate interactions with myosin Sliding filament model of contraction  The Neuromuscular Junction (NMJ) From Drosophila larva 183